(1) The present invention relates to a machine translation system for performing correct and speedy translation by the use of a plurality of different types of dictionaries for translation.
(2) Description of the Prior Art
Much attention has been paid to automatic machine translation systems of input original documents written in a first language into a second language by the use of a computer, of late. In these machine translation systems, the input original sentences are analyzed in view of each morpheme and its morphological construction as well as syntax, and divided into predetermined units for processing of words, phrases, or idioms. Then, a dictionary or dictionaries for translation are searched and each word is retrieved from the dictionary for every processing unit of the words and phrases thus divided, and when the corresponding words and phrases in the second language, i.e., translated words and phases are found in the dictionary, they are finally combined in accordance with predetermined translation rules and grammars, thereby obtaining their translated sentences.
In such translation systems as described above, it is normal to use a plurality of different dictionaries, e.g., a general purpose dictionary and a nomenclature dictionary in order to translate complicated natural languages, which human beings use as well as to produce desired translation including terminology which users of the system want.
The general purpose dictionary indicates the one into which words of all of possible parts of speech in the first language and their translated counterparts in the second language, consisting of the each of words and idioms, have been stored. Accordingly, when analyzing the syntax of the first language possible parts of speech are in turn determined, thus succeeding in the analysis in an early stage of search. However, since only standard words and phrases or idioms have been stored in the general purpose dictionary in view of translation, a good translation of the original cannot be expected.
In the nomenclature dictionary, since specific translated words and phrases, i.e., mostly terminology of nouns in each of particular fields have been stored therein, translated senses in good quality can be expected. However, since for the most part only nouns among the parts of speech have been stored in the nomenclature dictionary, the analysis of syntax often tends to.
Now, among the methods of retrieving words and idioms from a plurality of dictionaries for translation, there has been proposed heretofore a method of retrieving the parts of speech and phrases successively. In this method, however, as the intelligence and information to be used for the translation processing, those dictionaries including the parts of speech and translated words and idioms have a higher priority in the translation processing with respect to the contents of the dictionary for translation in the former dictionary, than those in the latter dictionary.
Since both the general purpose dictionary and the nomenclature dictionary alike have both merits and demerits described above, there was the drawback that even if any one of the two dictionaries was preferentially used for the retrieval of certain words and idioms, it could not sufficiently deal with the translation processing of various original documents.
For example, when the general purpose dictionary is given a higher priority than the nomenclature dictionary, an original sentence written in English for instance, which reads "The system has a large store." is translated into a Japanese sentence which reads "Sono shisutemu wa ogata no mise o yusuru." as the result of the retrieval of noun "mise (shop)" instead of "Kiokusochi (memory)". In this case, the translated sentence is grammatically correct but it is not at all a correct translation in its true meaning because it is a maltranslation.
On the other hand, when the nomenclature dictionary is given a higher priority than the general purpose dictionary, the original in English which reads "The system stores values." can not also be correctly translated into a correct Japanese sentence, because the nomenclature dictionary contains for the most part only nouns so that the translated Japanese may become somewhat "Sono shisutemu no kiokusochi no atai" as the result of the interpretation of a series of nouns, thereby failing to analyze its syntax.
Since an operator has to correct the translation errors by looking at sentences on a display of a machine translation system according to the prior art, it will take much time before correct sentences will be finally obtained finally.
For these reasons, a machine translation system has long been desired, wherein translated sentences can be obtained rapidly but in good quality by the effective use of both the general purpose and nomenclature dictionaries, as well as by controlling the priority orders of the two kinds of the dictionaries in accordance with the contents of the original in view of the parts of speech and terminology as well, used in the original to be translated.